Questions tagged [capillary-action]

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48
votes
3answers
13k views

When water climbs up a piece of paper, where is the energy coming from?

Take a glass of water and piece of toilet paper. If you keep the paper vertical, and touch the surface of the water with the tip of the paper, you can see the water being absorbed and climbing up the ...
23
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2answers
14k views

How does a sponge “suck” up water against gravity?

If I take a sponge and place it in a shallow dish of water (i.e. water level is lower than height of sponge), it absorbs water until the sponge is wet, including a portion of the sponge above the ...
15
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4answers
2k views

Why does string not wick down?

I regularly drink tea at work and I often reuse the tea bags (yes I know I'm a cheapskate). Yesterday afternoon I used a tea bag once and kept it in the cup in case I wanted another cup before I left....
10
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1answer
691 views

Sandstone getting soaked with water [duplicate]

I have seen someone putting a sandstone in water. With only about 10% of the stone sitting in the water. One could see the stone getting soaked with water. So there must be a force, which lets the ...
10
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2answers
5k views

How is the water meniscus at the edge of a capillary tube?

Suppose we have a capillary tube in which water can rise to a height of x cm. If we dip the tube such that the height above the surface is less than x, then how will the water meniscus be at the edge ...
9
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2answers
819 views

Does capillary rise violate hydrostatic paradox?

If $p$ is a pressure and $p_A = p_{\text{atm}} + hdg,\,$ $p_B = p_{\text{atm}}$, is hydrostatic paradox violated, shouldn't $p_A=p_B$?
8
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2answers
669 views

How is it possible for tall trees to pull water to heights more than 10m?

Which force actually drives water so high up, since pure atmospheric pressure will only get you up to about 10 meters if you're using suction and a long straw and yet tallest trees are over 100 meters ...
8
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1answer
276 views

Physics of dunking biscuits

Together with my 5 years old assistant, after endless observations breakfast after breakfast, we finally decided to be serious about it, and quantify a remarkable property of biscuits in milk. ...
7
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2answers
1k views

What physical forces pull/press water upwards in vegetation?

Each spring enormous amounts of water rise up in trees and other vegetation. What causes this stream upwards? Edit: I was under the impression that capillary action is a key factor: the original ...
6
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2answers
7k views

Capillary action and conservation of energy [duplicate]

When I dip a paper towel in a cup of water the water gets drawn up due to capillary action. How is this reconciled with conservation of energy, as it would seem on the surface that the potential ...
5
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7answers
17k views

Capillary tube of insufficient length

I was wondering if we have a very thin glass tube placed in a tub of liquid and the portion of the tube outside the liquid is lesser than the height to which the liquid can rise because of capillarity,...
5
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4answers
4k views

Why doesn't this capillary action generator work?

So I was doing a bit of reading. Apparently the obstacle to generating energy from the forces driving capillary action is breaking the surface tension at the top of a capillary tube. It is just ...
5
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3answers
599 views

Will a drop of liquid flow from from the wide opening to the narrow opening of a thin funnel by the effect of air pressure?

We have a funnel that is thin enough to keep a drop of liquid inside it as shown in this figure. Assuming that the funnel is placed on a horizontal table, will the drop flow from the left side to the ...
5
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1answer
671 views

Contact Angle In Capillary

One Professor recently told me that in an insufficient length capillary, the contact angle doesn't change, its an inherent property which does not change. If the edges of capillary are extremely sharp ...
5
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1answer
9k views

Surface tension and capillarity

The cause of surface tension is said to be asymmetry in the forces experienced by the molecules at the surface due to different interactions with air and liquid, but then the same argument also ...
5
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0answers
453 views

Can water drip from a capillary tube top? Perpetual motion?

In a normal capillary tube (ex: tube A), where the water doesn't travel as high as the tube's height, h, the meniscus formed is "normal" (concave, as seen in tube A). From previous posts, I ...
5
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1answer
414 views

Does gravity affect water permeability?

Suppose I have an approximately rectangular prism composed entirely of folded paper. If I place 600lbs on top of these rectangular sheets of paper, the paper should compress. How does this affect ...
4
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2answers
2k views

Does folding a paper towel help dry your hands faster by creating interstitial forces?

The question is based on a TEDx video, where the speaker claims that folding a paper towel before using it creates interstitial forces which help dry your hands faster. The question: Does this ...
4
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1answer
247 views

How fast does liquid rise in a capillary tube?

Take a small diameter tube, stick it in water, and surface tension will drive the fluid up through the tube. How fast is the fluid moving through the tube during this process? Here's my attempt: ...
4
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1answer
957 views

Bent capillary tube

What would happen if I bend a capillary tube and use it as shown in figure? 1.Will the water(or any other adhesive liquid) level remain same as before bending? 2.or it will come up till end? 3.Or ...
4
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2answers
2k views

How to move a bubble which is trapped by the capillary pressure?

I have a question about how to move a trapped bubble in a tube. If we assume to have a horizontal tube, with water on each side of the bubble. The point to the left of the bubble is point 1, while ...
4
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1answer
694 views

Capillary Rise and a Surfactant - Experiment

Proposed Experiment: Consider a capillary tube, dipped in a container filled with water (Assume that the tube doesn't topple over or sink, it is fixed in its position somehow). It is obvious that we ...
4
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1answer
784 views

Why is the angle of contact different for a meniscus and a droplet in the same water/glass/air environment?

There's gravity, there's adhesive and cohesive attractive forces. Fair enough, most materials seem to compare water to mercury in capillary tubes when explaining capillary action and above properties ...
4
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1answer
277 views

Is Pascal's law incorrect?

Consider the figure given below. Here I'm gonna talk about capillarity. The liquid inside the beaker as well as the column is water. As water has a tendency to rise in the capillary as shown, doesn't ...
3
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3answers
3k views

How is sweating a pipe an example of capillary action?

I learned how to sweat a pipe today from my father. If you're not familiar with the process, this might help. One thing that jumps out at me is this line (from the above link, as well as my father's ...
3
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1answer
44k views

Problem understanding the capillary action equation

As you know the equation of capillary action id given by: $h=\dfrac{2\gamma\cos\theta}{\rho gr}$ Where: $h$ is the height the liquid is lifted, $\gamma$ is the liquid-air surface ...
3
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1answer
2k views

Can capillary forces be used to make hydro electricity?

Could a device with very thin columns of glass or something that attracts water more be used to pull water up and then release it to drive generator and perhaps add vacuum. I have been wondering ...
3
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1answer
439 views

How does a piece of paper manage to pump out the water from a bowl

When we go to bed at home, we started to put a bowl of water on the radiator (the air gets a bit dry). By instinct I put a soaked piece of paper (e.g. toilet paper) into the bowl and let it touch the ...
3
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2answers
1k views

Surface tension and capillary rise

The expression for the height rise in a capillary tube is well known, and the surface tension of the liquid air interface is involved. But as I understand the adhesion force between the water and ...
3
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4answers
4k views

Size of a glass capillary for noticable capillary action

How big would a glass capillary have to be to have noticable capillary action? Also, does capillary action happen in plastic tubes?
3
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2answers
157 views

Does molten solder flow towards a heat source?

When soldering both plumbing and wiring I have heard the advice that you shoulf apply solid solder opposite to your heat source, since the solder "will flow towards the heat" once it melts. Is this a ...
3
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1answer
155 views

Equidistant coffee rings in a mug: pinning boundaries coupled with migration of solute or just sip volume?

I understand that you get coffee rings on a table as a result of solute migration (solutocapillarity) towards the pinning of the circumference of the coffee ring [Deegan et al.]. Below is an ...
2
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1answer
391 views

Why do new towels dry better after a few uses?

Most of you will be familiar with the phenomenon: you have bought a new towel and you first have to wash it or use it a couple of times before it starts to work properly, i.e. dry your body after ...
2
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2answers
186 views

Capillary length and Bond number confusion

The Bond number represents the ratio of gravity forces to surface tension forces, and is defined as $$ Bo = \frac{\rho g L^2}{\sigma}$$ where $\rho$ is the fluid density, $g$ is gravitational ...
2
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1answer
337 views

Meniscus in U-shaped capillary?

What does the meniscus look like for a U-shaped capillary? From similar questions, I learned that the total height (labeled as h) reached by the water in the un-bent capillary is less than the total ...
2
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1answer
437 views

Effect of acceleration on rise of liquid in capillary

What would be the effect of vertical acceleration on the rise of liquid level in a capillary tube. Will the liquid not rise if we provide the system a downward acceleration equal to $g$ ? Consider ...
2
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1answer
3k views

How does capillary action work in tubes which are closed at the top?

In all textbooks the examples and descriptions use tubes which are open at both ends. Our teacher remarked that if it were closed at one end like a test tube (albeit a thin one) even then capillary ...
2
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2answers
13k views

Why does a paper towel absorb water upwards?

When I touch a paper towel to a drop of water I can see the water move upwards into the paper towel. What force is responsible for this gravity defying phenomenon?
2
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0answers
432 views

Conservation of Energy in Capillary Tube

The capillary action lets a liquid rise in a narrow tube to a certain height. In this, the liquid gains some potential energy. According to the Conservation of Energy, the energy must come from ...
2
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0answers
251 views

Capillary action column height in a tube fitted inside another tube?

I was thinking about how would capillary action change in a tube (classic example) and in a tube fitted inside another tube (considering water as the liquid involved). Height of liquid column: where:...
1
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4answers
829 views

Doubt in capillary rise

The capillary action formula is given as: $$h=2T/ρgR$$ where h is the capillary rise, R is the radius of curvature of miniscus, ρ is density, g is force of gravity and T is the surface tension. Now ...
1
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1answer
444 views

Why don't we include the adhesive and cohesive force while calculating rise in a capillary tube?

The contact angle of a liquid solid interface is explained by saying that the liquid surface must be perpendicular to the resultant of adhesive cohesive and gravitational forces acting on it, since it ...
1
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2answers
89 views

Why does water hold up between the teeth of my comb?

Image for reference: As can be seen in the above image, whenever my comb comes in contact with water, a little of it is trapped between the teeth. This happens whether I dip it in still water or ...
1
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1answer
2k views

Capillaries in series

The velocity of fluid of viscosity $\eta$ through a capillary of radius $r$ and length $l$ at a distance $x$ from the center of the capillary is given by; $v=\frac{P}{4l \eta }(r^2-x^2)$ (where $P$ is ...
1
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1answer
43 views

Pressure variation in a capillary tube

The following image shows capillary tubes placed in beakers containing water and mercury: We know that the rise or fall in the level of liquid in a capillary tube is given by Jurin's law: $$h=\frac{...
1
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1answer
35 views

Will water spill out of filled capillary tube, if raised from water?

if to raise a filled capillary tube from the level of water, will the inside will spill out? or will it keep stuck inside? imagine a capillary tube put in water, the water rises inside the capillary ...
1
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1answer
413 views

Capillary Perpetual Motion

Can anyone figure out what is wrong with this perpetual motion machine? What part of it violates physics? I found it on a website a while ago, and I couldn't figure out what was wrong with it. Thanks, ...
1
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1answer
143 views

Concept of contact angle, cohesive and adhesive forces

I was reading the topic of contact angle from a book and I couldn't exactly understand it. The first photo depicts the general case when a solid surface touches a liquid surface. $Fs$ is the adhesive ...
1
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1answer
63 views

Capillary being pulled out of a large reservoir

For the above question, they've equated the excess pressure across the meniscus to the pressure due to height of liquid column in the capillary, as follows: This clearly gives RH = constant, hence ...
1
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1answer
85 views

Can particles be sucked into a pipe while water is pushed through it

The picture below shows a piece of equipment dentists use, called a "water scaler". As you can see, there's water spraying out of it through a very small hole right in front of the bend. I've been ...